For decades we have known that changing an animal's visual experience during an early postnatal period affects the response properties of neurons in the cortex. While much is known about the anatomical and physiological visual changes in cortex that result from exposing the animal to different visual environments, little is known about the afferent patterns of activity from the dorsal lateral geniculate nucleus (dLGN) that drive these changes. Because monocular lid suture (MS), but not monocular retinal inactivation (Ml), leads to a depression of the deprived eye response in visual cortex, we hypothesize that dLGN neurons will show different patterns of activity under these two conditions and the differences will encompass the salient features for response depression to occur in vivo. To test this hypothesis, we will record extracellular dLGN unit activity from head-restrained and freely behaving juvenile rodents under MS, Ml and normal viewing conditions. Since adults do not show a deprivation induced depression, we hypothesize that dLGN activity may be changing as the animal matures. To test this hypothesis, we will repeat our deprivation experiments in adult animals and compare these results to those obtained in the juveniles. This research will shed light on the patterns of neural activity that lead to amblyopia. By understanding the underlying activity that leads to this disorder, new methods for treatment may become apparent. [unreadable] [unreadable] [unreadable]